Lupinus rivularis
Riverbank lupine, also known as streambank lupine, provides striking and long-blooming visual interest and a faintly pleasant scent; with iconic, radially-compound leaves and whorls of bluish-purple pea-like flowers on vertical spires. It is fast-growing, forming a large shrub-like plant that produces pollen and nectar for bumblebees, other native pollinators and beneficial insects. By fall, the flowers die back into spiraling seed capsules considered ornamental to some (like us!).
- Plant type/canopy layer: deciduous, perennial, herbaceous plant
- Size at maturity: 36”- 48” tall, 24”-36” wide
- Light requirements: full sun to part shade
- Moisture requirements: dry to moist soil
- Bloom time: March - August
- Growth rate/ease: fast growing, easy to grow
- Wildlife support: flowers attract and provide nectar to hummingbirds, adult butterflies, bees and other insect pollinators; overall plant attracts and supports beneficial and pest eating insects and is a caterpillar host plant and larval food source for native butterflies and moths
- Native habitat/range: commonly found in coastal habitats, meadows, and riverbanks west of the Cascades in south western Canada, WA, OR and northern CA. Portland Plant List - yes.
- Special features & uses: pollinator gardens, rock gardens, raingardens and meadowscapes, erosion control, nitrogen-fixation, supports hummingbirds
Gardening with Riverbank Lupine: Many gardeners are less familiar with this species than its cousin, large-leaf lupine. The leaves and flowers of riverbank lupine are smaller, while the overall plant tends to be larger and branching in form, giving it an open, airy look. It also tolerates significantly drier soils and often behaves as a biennial: mostly vegetative the first year, with a few flowers, then displaying an impressive amount of blooms in the second year. The vegetation of this species can become quite woody and gnarled. Many gardeners choose to cut it back after each growing season. It is also notably short-lived, but can readily reseed itself in the garden. It is exceptionally useful for erosion control as well as meadow restoration, with its nitrogen-fixing roots.
Photo credit: Steele Acres Native Willamette Valley Seed